The invention herein is directed toward control systems, and particularly control systems for electrically commutated, variable speed (i.e. ECM) motor driven compressors used in heat pump systems.
At present, there is considerable speed variation from unit to unit in electrically commutated, variable speed motor driven compressors. The speed variation in typical electrically commutated, variable speed motor driven compressors may be as great as twenty (20) percent from a given nominal value, particularly with open loop electrically commutated motor controllers.
This speed variation, depending upon the particular compressor installed in the heat pump system, results in poor control over the operation of the entire heat pump system, possibly causing discomfort to individuals located in the spaces to be heated, ventilated or air conditioned by the heat pump system. Additionally, since the compressor speeds are not controlled effectively, motor speeds over time may be too low or too high with respect to optimum or nominal design. This detrimentally affects the long term maintenance and operability of the compressor and heat pump system. In fact, the lack of speed control can have clearly destructive effects upon many of the individual equipment components comprising the system itself.